Studies in progress and projected for the near future include an examination of "Coupled systems". The results for separate enzyme systems suggest that coupling FDPase and PFK should produce a situation in which the concentration of F-6-P will attain a non-zero steady-state value with increased amounts of PFK, i.e., alpha yields beta F-6-P is rate-determining. This experiment will not only serve as a check on the above results but will also supply information concerning possible protein-protein interactions. Such "coupling of enzymes" experiments also approximate more closely conditions in the cell. Additionally we will investigate the anomeric specificity of PFK activation by substrate analogs of F-1, 6-diP. The kinetics of activated and non-activated systems will be compared, and the interactions of the analogs with spin-labeled PFK will be monitored by ESR. Finally the rapid quench studies in progress with PFK will be completed.